Larsson, Catarina

Abstract [en]

Loss of marine ecosystem resilience can lead to abrupt changes in ecosystem structure, so called regime shifts, which affects dynamics and function of the ecosystem. Loss of ecosystem provisioning services can have a substantial impact on human well-being. Reversing an ecosystem back to its original state after a regime shift can be difficult, costly and impossible. Management strategies applied after a regime shift can have a different future outcome than applied before the regime shift. In the face of climate change and intensification of nutrient loading and fishing, there is a need to understand how to manage marine ecosystems in order to prevent future regime shifts and to understand the outcome from applied management strategies. The Central Baltic Sea is a heterogeneous water body with hydrographical differences from the south to the north, and with Gotland basin suffering with hypoxic conditions and summer algal blooms and it provides an interesting opportunity to explore ecosystem response on a smaller spatial scale. Here I combine ecosystem modeling and future scenarios to explore past ecosystem dynamics and by testing future management strategies from two initial states explore the ecosystem outcome and resilience. The present study have successfully constructed an Ecopath with Ecosim food web model of Gotland basin from 1980 to 2009 where the results shows that past, i.e., 1980-2009 dynamics were in line with the changes occurring on a larger scale, the Central Baltic Sea. Results from future projections show that the level of nutrients has a large impact on the future outcome of the ecosystem and the influence initial ecosystem states have for future outcome is found to be low.

Finally, I discuss drivers and processes behind the past changes and future projections in Gotland food web, bringing insights to the role of initial ecosystem state for future ecosystem-based management.